AC COMBINATION VOLT/AMP DIGITAL PANNEL METER

It's clearly not that difficult to produce a digital meter that would fit our needs, that's not the issue.  That has been discussed here several times.  The issue is what it would cost to bring such a product to the table and still make it worthwhile for the builder.  The easy part is actually designing the meter, and even designing and laying out the circuit board for the product is no sweat.  I have a few products that I produce that I've done all of those steps for.  Consider the Super-Chuffer, Chuff-Generator, LED Lighting Regulator, and the YLB - RailSounds Battery Replacement.

Now, let's get to the harder parts.  The injection molded case for the meter, just the tooling will bury you.  Next is the cost of components and assembly.  I can tell you with certainty that it's not as cheap as you might imagine building stuff in the quantities required for a limited market, and that comes from experience with my little suite of products.  My biggest issue is trying to actually do all the steps of producing them from the design through the manufacturing and packaging and still bring them to market with a price that makes sense. Some will say I miss the mark at times, that's the realities of life.  The eBay meters have set the bar very low as far as pricing, $5-6 won't even buy the components at the pricing I can get for small quantities (100-200).

I have deliberately steered clear of having to create custom casework for a product as just looking into the startup costs convinces me that I'd never get my investment back.

Dave Zucal posted:

TedD, all we need is for the price to be more admirable for purchasing the RRampMeter meter. This meter is a great and accurate meter, just very expensive.

 I rest my case, that's about the price I'd end up with if I had to supply custom packaging for the product.

Got it. I'll go back under the rock. TW

Thanks for that comment GRJ, it make a lot of sense then why the RRamp meter cost what it does. I'm sure the price goes down as production goes up. We are definitely a small audience for these products. 

Here is a link to mfg's and suppliers..hard to tell who does what?

https://www.alibaba.com/countr.../CN/panel-meter.html

gunrunnerjohn posted:

It's clearly not that difficult to produce a digital meter that would fit our needs, that's not the issue.  That has been discussed here several times.  The issue is what it would cost to bring such a product to the table and still make it worthwhile for the builder.  The easy part is actually designing the meter, and even designing and laying out the circuit board for the product is no sweat.  I have a few products that I produce that I've done all of those steps for.  Consider the Super-Chuffer, Chuff-Generator, LED Lighting Regulator, and the YLB - RailSounds Battery Replacement.

Now, let's get to the harder parts.  The injection molded case for the meter, just the tooling will bury you.  Next is the cost of components and assembly.  I can tell you with certainty that it's not as cheap as you might imagine building stuff in the quantities required for a limited market, and that comes from experience with my little suite of products.  My biggest issue is trying to actually do all the steps of producing them from the design through the manufacturing and packaging and still bring them to market with a price that makes sense. Some will say I miss the mark at times, that's the realities of life.  The eBay meters have set the bar very low as far as pricing, $5-6 won't even buy the components at the pricing I can get for small quantities (100-200).

I have deliberately steered clear of having to create custom casework for a product as just looking into the startup costs convinces me that I'd never get my investment back.

Dave Zucal posted:

TedD, all we need is for the price to be more admirable for purchasing the RRampMeter meter. This meter is a great and accurate meter, just very expensive.

 I rest my case, that's about the price I'd end up with if I had to supply custom packaging for the product.

All very good points John makes, but could the housing and meters of the $8 meter be reused (discard the existing PCB) and design a new PCB that would meet our needs. This would address the production cost of the molded case.

For the issue of assembling the board, leave it in a kit form and let the individuals put it together. A kit would limit the number of people that would purchase, but a solution would be available and maybe some OGR member might take on the task of assembling the units for those of us who don't want to solder.  

I guess it comes down to, does it pay to design a new meter or go with the RRampMeter.  The RRampMeter goes for $60 - $110 price range, depending on the model/amperage you want.  Are there any estimates out there on the cost of parts for a new designed PCB to be used in the $8 enclosure w/meters?  Any estimated pricing close to the RRampMeter would kill the home made solution.

Bob D

I personally wouldn't consider buying a meter and salvaging the case as you can't count on that meter being available for a long period of time, so you've just designed for a part you can no longer get.  I don't do any of my commercial products with salvaged Chinese parts as these tend to be a flash-in-the-pan as far as availability.  I do use inexpensive Chinese parts when available, but they're generic parts that are available in the US marketplace, usually at a higher price as a rule.

Since I saw no market, I didn't see any reason to take it further. We had an interesting discussion on a true-RMS meter some time back, and it's clear that it's possible to do a quality product, I just don't think the time and effort would be justified as a commercial venture.

As for the kit idea, it works with my insulated track signal driver as I specifically designed it to be all thru-hole and easy for even a novice solderer to be able to assemble. 

For something like the meter, it would probably be a bunch of SMT parts, and those are a different matter.  The time to assemble just doesn't compete with automated assembly.  I've hand assembled enough SMT designs that I don't really want to do that as a steady diet.  In order to go for assembled boards, you have an entry cost for a project in the hundreds of dollars for initial tooling, and then a piece price for the boards.  In order to get decent prices on parts and assembly, you have to do a significant quantity, typically at least 100 and more for the competitive prices.  Once they setup the assembly, it's just the operator watching the machine work and feeding it a panel of new boards periodically.  Every time they have to setup for a new board, it's labor intensive.

I never got a reply from the ebay seller I asked about the AC meters in our ranges. So much for that I guess?

I have contacted alibabas mfg request a quote on what we are after....i referenced we use 18vac power and 0-10 or 0-20 ac amp range..what and see..what do we have to loose

At the very least one of these:

whoops ignore this one..couldnt delete

with one of these should work.

Nice find WillyGee, with a matching amp meter along side it.

Interesting response from a meter mfg:

http://message.alibaba.com/mes...YO0Bfw*/21/quotation

Problem with Alibaba is they want to sell you large quantities, onesie-twosie orders are not really possible for most of them.

Interesting indeed!  Your link takes me to a Alibaba login page so I think it only works for you.

But assuming the photo is their response, are you going to take him up on his offer, "You can try 1-2 sample for testing"?

The peanut gallery can comment but I'm thinking a $20 TRUE RMS combo AC digital panel meter with 0-200V (0.1V resolution) and 0-20A (0.1A resolution) measurement range is very usable for O gauge. 

There is still the matter of the 90-260VAC power supply range.  My opinion is it would be easier to modify this meter for O-gauge operation (e.g., change the power supply to accept 18V AC) than to design one from the ground up.

If you're actually talking to the meter manufacturer as his response implies, did you ask if they would quote a modified version that operates with a 12-24V AC (or whatever) power supply rather than the 90-260VAC power supply?

I need to clarify specs first...90-260VAC power supply range..say whaaaaat

I notice it also said "Isolation Power Module", that implies he needs an isolated power supply.  However, I suspect you could remove a couple of components or change values and get down to earth with the power supply requirements.

Here's a 120V isolation transformer for $7.24.

willygee posted:

I need to clarify specs first...90-260VAC power supply range..say whaaaaat

The digital electronics and LED display circuit operate at low-voltage DC (3-5V DC or so).  What I'm saying is you must separate the measurement capability from the power-supply requirement.  Since 99.9% (I'm making this number up for effect) of these panel meters are used to measure AC wall-outlet goings-on, it is convenient to have them operate at wall-outlet line voltage.  Hence these meters must have some kind of AC-to-DC power supply that accepts >90V AC and converts it down to 5V DC.  As I showed earlier you can get a tiny module that does this for about $1 quantity 1...in other words it's not difficult/expensive.  These AC-to-DC converter modules are also isolated as they have a transformer:

As I suggested (speculated) earlier, when these AC digital voltmeter/ammeter modules first came out, you were required to supply them with low-voltage 5V or 12V of DC isolated power which meant a few bucks in parts for a DIY'er.  Again, this DC is needed to power the electronics and LED display.  Apparently the manufacturers discovered or were told that it's a nuisance to come up with supply and simply used the available 120V or 240V AC voltage to provide the low-voltage DC power supply...this only cost them less than $1 in parts at volume offshore pricing.

So what you want to know is if they can modify the power supply on the combo meter to operate at 12V-24V AC (the power supply)...but still measure 0-200V AC with 0.1V resolution and 0-20A AC with 0.1A resolution.  It's easy for me to say but all they need to do in principle is change the parameters on a few low-cost components.

If they don't modify a design for less than a commitment of 10,000 units (or whatever) then so be it and it becomes up to an enterprising O-gauge enthusiast to modify* the combo meter's power-supply to operate with a power supply of 12V-24V AC (or whatever) and yet measure the original 0-200V AC and 0-20A AC. 

  *in the case of your $8 combo meter, by "modify" I mean un-soldering and replacing with a few low-cost components in the power supply circuit.  This measurement capability is still limited by the 1V voltmeter resolution but it should at least operate/measure across the O-gauge track voltage range (rather than flaking out when current goes above 5 Amps as your video suggests).

Stan, what would happen to the measurement capabilities if we used a step up transformer (from the bay) to increase our 18vac to the 90-240 range they specify?

Right...and good thinking!  The digital electronics/display circuitry of these widgets typically requires, say, 1 Watt of power which is quite modest as transformers go.  So you don't need a lot of "iron" as-it-were. 

I believe it would work to step-up the 18VAC to 100VAC using a tiny transformer.  You then need to find the point in the measurement circuit where it samples the incoming AC voltage.  And rather than looking at the stepped up voltage...you need to jumper that point to the 18VAC voltage which is what you really want to measure.   Again, the idea here is to separate the power supply circuit from the measurement circuit.

The trick is to find an economical off-the-shelf transformer with a suitable turns ratio (1:5, 1:6 or so).  The 1:1 low-power isolation transformer that GRJ found is probably tiny and has the right amount of "iron" (2-3 Watts per the spec)...but ignoring the turns-ratio issue, at $7 each qty 1, if that's the going rate for low-power transformers then, "Houston, we have a problem."

I'd be more inclined to look for a way to run the meter on low voltage if I'm going to have to modify it anyway.  Pumping 100 volts or more into it seems like the wrong way to go.   I see a rather large power resistor, my guess is that's dumping most of that voltage to drop it for the regulator circuit.  It would seem pretty simple to change that if you were going to hack the meter.

Wonder what the silver item behind the green 2 terminal blocks that might be labeled 'AR' just above R26 is for? Looks like it might be some type of adjustment maybe?

I think I like the low voltage plan as well, the 90-100 volts has a much better 'bite' to it than the 18 vac. With everything else being low voltage, I can see myself forgetting it's there. Well at least once anyway...  

gunrunnerjohn posted:

I'd be more inclined to look for a way to run the meter on low voltage if I'm going to have to modify it anyway.  Pumping 100 volts or more into it seems like the wrong way to go.   I see a rather large power resistor, my guess is that's dumping most of that voltage to drop it for the regulator circuit.  It would seem pretty simple to change that if you were going to hack the meter.

And i am willing

gunrunnerjohn posted:

I'd be more inclined to look for a way to run the meter on low voltage if I'm going to have to modify it anyway.  Pumping 100 volts or more into it seems like the wrong way to go.   I see a rather large power resistor, my guess is that's dumping most of that voltage to drop it for the regulator circuit.  It would seem pretty simple to change that if you were going to hack the meter.

The "regulator ?".... has this for identification:  6203A over161/44

rtr12 posted:

Wonder what the silver item behind the green 2 terminal blocks that might be labeled 'AR' just above R26 is for? Looks like it might be some type of adjustment maybe?

I think I like the low voltage plan as well, the 90-100 volts has a much better 'bite' to it than the 18 vac. With everything else being low voltage, I can see myself forgetting it's there. Well at least once anyway...  

RTR...a very minnie pot i believe..

Of course the annotated photo is of the $8 YB4835VA combo meter which only offers 1V voltage resolution.  While the $20 True RMS XL5135AC combo meter (with 0.1V voltage resolution) may have a similar un-isolated power supply, I suggest taking a look before popping the champagne cork or firing up the soldering iron.   But, yes, it could be as "simple" as tacking another resistor across (in parallel) with that 100 ohm "voltage dropping resistor" - so maybe no component removal / de-soldering.

So are you going to request 1-2 samples of the True RMS meter?  In the OEM product design world, the term "sample" means at no charge.

Yes, that is what I thought it might be. Wonder what it adjusts?

Highly unlikely, but could it possibly adjust the input voltage in some way? Surely we couldn't be that lucky, it's probably for calibration or something that ruins the meter if you touch it???

I am out of my league here, but saw it sitting there and was just wondering...

Hmmm... I see there is another one labeled VR, up a little and to the right about 1/3 across the board, Stan, GRJ???

AR & VR... Amp range and Volt range???

willygee posted:

gunrunnerjohn posted:

I'd be more inclined to look for a way to run the meter on low voltage if I'm going to have to modify it anyway.  Pumping 100 volts or more into it seems like the wrong way to go.   I see a rather large power resistor, my guess is that's dumping most of that voltage to drop it for the regulator circuit.  It would seem pretty simple to change that if you were going to hack the meter.

The "regulator ?".... has this for identification:  6203A over161/44

https://www.google.com/search?...mp;ie=&oe=#spf=1

rtr12 posted:

Hmmm... I see there is another one labeled VR, up a little and to the right about 1/3 across the board, Stan, GRJ???

AR & VR... Amp range and Volt range???

Yes. To adjust the accuracy of the voltage reading and the amperage reading against a trusted better meter or source.

willygee posted:

At the very least one of these:

whoops ignore this one..couldnt delete

with one of these should work.

Those seem to answer the need...

The link...

http://www.ebay.com/itm/Yeeco-...f:g:5VwAAOSw2xRYkfQ-

stan2004 posted:

Of course the annotated photo is of the $8 YB4835VA combo meter which only offers 1V voltage resolution.  While the $20 True RMS XL5135AC combo meter (with 0.1V voltage resolution) may have a similar un-isolated power supply, I suggest taking a look before popping the champagne cork or firing up the soldering iron.   But, yes, it could be as "simple" as tacking another resistor across (in parallel) with that 100 ohm "voltage dropping resistor" - so maybe no component removal / de-soldering.

So are you going to request 1-2 samples of the True RMS meter?  In the OEM product design world, the term "sample" means at no charge.

I have got to restate the specifications:stan if you list the more technical specs that we want i will copy and paste and resubmit.

cjack posted:

willygee posted:

At the very least one of these:

whoops ignore this one..couldnt delete

with one of these should work.

Those seem to answer the need...

The link...

http://www.ebay.com/itm/Yeeco-...f:g:5VwAAOSw2xRYkfQ-

yup..2 meters per TIU channel..lot of square holes...

cjack posted:

rtr12 posted:

Hmmm... I see there is another one labeled VR, up a little and to the right about 1/3 across the board, Stan, GRJ???

AR & VR... Amp range and Volt range???

Yes. To adjust the accuracy of the voltage reading and the amperage reading against a trusted better meter or source.

I was afraid of that. Oh well...  Maybe WillyGee will get somewhere with the Alibaba folks for the combo meter in a reasonable quantity, but that may be a long shot too?

The chip beside the connector reads:  + -  over MB6S   rectifier maybe?

The MB6S is a bridge-rectifier.  It is most-likely converting the 90V-240V AC into DC.  The hi-voltage DC is then dropped via the 100 ohm resistor and then regulated to 3V DC by the 6203 chip.

If starting a dialog with that True RMS meter manufacturer, to keep things really simple I'd keep the meter specs as-is...in other words 0-200V AC with 0.1V resolution, and 0-20A AC with 0.1A resolution.  The only difference is you want it powered by 12V-24V AC/DC instead of 90-240V AC.  If this means having 4 wires (2 to the measured AC voltage, and 2 to 12-24V AC/DC power source, that's fine).  The reason to have 4-wires is to allow an independent power source to keep the meters running irrespective of power supply voltage.  This way you can have this monitoring a conventional track which might drop down to 5V AC or even go to 0 during Direction changes.  Having it powered by AC or DC should not be a problem since the power supply ultimately becomes low-voltage DC anyway.

stan2004 posted:

The MB6S is a bridge-rectifier.  It is most-likely converting the 90V-240V AC into DC.  The hi-voltage DC is then dropped via the 100 ohm resistor and then regulated to 3V DC by the 6203 chip.

If starting a dialog with that True RMS meter manufacturer, to keep things really simple I'd keep the meter specs as-is...in other words 0-200V AC with 0.1V resolution, and 0-20A AC with 0.1A resolution.  The only difference is you want it powered by 12V-24V AC/DC instead of 90-240V AC.  If this means having 4 wires (2 to the measured AC voltage, and 2 to 12-24V AC/DC power source, that's fine).  The reason to have 4-wires is to allow an independent power source to keep the meters running irrespective of power supply voltage.  This way you can have this monitoring a conventional track which might drop down to 5V AC or even go to 0 during Direction changes.  Having it powered by AC or DC should not be a problem since the power supply ultimately becomes low-voltage DC anyway.

Won't the "DC" part confuse them?

If you thought to ask, then it probably will confuse them so you can leave it as AC power only.  Separately, going from 2-wire (self-powered) as it is now to 4-wire may confuse them too.  So I suppose the simplest is to keep the measurement ranges as-is, and simply change the voltage input (both the power-supply and measured voltage) to 12-24V AC.

I will specify 12-24 vac 60hz...2 wire self powered 0-10 ac amp. Do i need to mention RMS or is it assumed?

I'm guessing since this is generally meant for the AC line voltage, they are storing the peak and scaling times .707 rather than some software that computes the RMS.

I think, though, that it's repeatability that is the most important. I wonder how Lionel does the ac voltage with their add on meter for the ZW-C. I see they went with analog meters for the ZW-L. 

I think RMS is assumed.

If they only entertain power supply modification to the non-RMS meter type like the $8 unit you have, if they could make it 0.1V resolution that would be worth considering in my opinion.  That is with the known prices, it's hard to say if the O gauge crowd will pay double or triple for true-RMS capability.  The O-gauge world seems to have come along fine using non-RMS analog panel meters which are just a few dollars each. 

It might be possible on a meter like this to separate the power from the measurement and just provide the power with a sky-wire from an isolated source.